Dual Axis with Phase Control

Dual-Loop Control

Dual-loop control is achieved by using two outputs from a VR9500 or VR10500 I/O unit. The drive and COLA outputs from one controller are used to drive two different shakers with the same test profile. The result is a synchronized pair of shakers, ideal for full-system testing of a larger device.

VR9500 I/O Unit

Vibration Research’s best-selling control hardware for vibration and shock testing. Scalable to 128 channels and compatible with all electrodynamic and servo-hydraulic shakers. Features include up to 200kHz sample rate and 2 outputs.

VR10500 I/O Unit

Vibration Research’s high channel count control hardware for vibration and shock testing. Scalable to 512 channels and compatible with all electrodynamic and servo-hydraulic shakers. Features include up to 256kHz sample rate and 4 outputs for multiple shakers.

Test Profile Settings

• Vary phase on Loop 2 (-180° to +180°)
• Set modifier to zero to disable loop
• Independent, differential, magnitude-only, and equal outputs control
• Create a waveform for each loop

Dual-Axis Applications

SINE
Enter two of four values (acceleration, frequency, velocity, or displacement) and the software will calculate the rest.

The shakers will use the same Sine profile, but the user can adjust the phase angle between the two outputs (+/- 360 degrees).

Sine offers four control methods:

1. Independent control: The outputs are controlled independently with a separate control loop on the phase between the first selected control channel for each loop. Each loop may be operated individually, and the magnitudes and relative phases of the two loops vary.
2. Differential control: The difference between the two outputs is used to null the magnitude and phase difference between the first control channel on each loop.
3. Magnitude-only control: The two outputs are always in phase; only the relative magnitudes vary to null the magnitude difference between the first control channel on each loop.
4. Equal outputs: The two outputs are always the same magnitude and phase; both shakers perceive the same drive signal. Essentially a software-level BNC T-Adapter.

The Sine graph settings include a control loop section, and the user can select which control loop demand, control, tolerance, and abort traces to plot. The transmissibility plot allows either loop to be used as the reference.

RANDOM
Run Controlled spectrum random tests (tests with a spectrally shaped Gaussian amplitude distribution).

The matched phase between the two outputs is auto-controlled.

Random offers three control methods:

1. Equal outputs: The two outputs are always the same signal. Essentially a software-level BNC T-Adapter.
2. Magnitude-only control: The drive output controls the magnitude of the first control channel. The COLA output controls the magnitude of the second control channel.
3. Magnitude and phase control: The magnitude and phase of the drive output are based on the first control channel, and the magnitude and phase of the COLA output are based on the second control channel.

The COLA trace is available on the following graphs for test profiles configured to Magnitude-only or Magnitude and Phase control:

• Output Drive vs. Frequency
• Output Drive vs. Time
• Output Drive vs. RMS History

SHOCK
Run standard classical shock pulses as well as (optional) user-defined or SRS synthesized transient pulses.

SHOCK RESPONSE SPECTRUM (SRS)
Perform a Shock Response Spectrum (SRS) analysis. Run a shock pulse defined by a frequency vs. G peak table.